3M 94 Primer – Application as a TPE Glue / Cold Weld

[Wheezer]

With “Coronoa Virus Time” on my hands and looking onto ways to attach silicone nipples to my TPE doll, plus some odd tears and repairs, I have been experimenting with various items. I overlooked several small white cans on the shelf, but then started tests with the solution.

The item is “3M 94 Primer”, a liquid used as an industrial tape primer. It is applied to a base material, allowed to flash off, then will permit you to apply tape firmly to odd shapes, such as around sharp bends. It is primarily used in automotive detailing applications.

00-20200808_230139(640).jpg (154.8 KiB) Viewed 14491 times

The primer is a light amber liquid that chemically has many of the components that are known to work on TPE, such as Cyclohexane, Xylene and Ethylbenzene. Plus a few additional interesting compounds such as Ethyl Alcohol, Ethyl Acetate, Acrylate Polymer, Chlorinated Polyolefin and Epoxy Resin. The SDS lists it as an “Adhesion Promoter, Primer”. Cleanup can be done with 70% Isopropyl alcohol.

First tests were done with TPE scrap items. These included clean cuts, ragged cuts/tears, deep cuts and joining similar and dissimilar brand TPE. In each case the item was cleaned with Isopropyl alcohol and allowed to dry. Then each side of the item to be joined was lightly spread with the primer, using a toothpick. Parts were then joined and allowed to set. The cut joins all held well and retained the elasticity of the original TPE. Even placing some joins under extreme stress (bending back 180 degrees) did not lead to separation. Both similar and dissimilar TPE bonding worked well and held solidly. The solution appears to work as a TPE glue or “cold weld”, useful for repairing cuts, damages and joining TPE parts.

After doing a number of tests I came up with a process that seems to work for me and results in a good join and smooth surface when finished. Most steps are not unusual from normal TPE glue application.

• 1) Test fit wound. Position so that the area is relaxed and will naturally stay closed and compressed.
  2) Clean wound with 70% Isopropyl alcohol. Allow to dry
  3) Open wound gently and apply a small amount of solution to both sides of the wound as deep as possible. Use a toothpick to apply a very light coating.
  4) Close wound and allow it to set for 5 minutes. Note that very deep wounds might require these two steps to be repeated to get to the top edge of the wound.
  5) (OPTIONAL) Apply solution to a Q-Tip and then roll it wet over the wound area. This should fill in the upper portion of the wound and blend it together. Do not get concerned if the TPE gets a bit “crinkly”, this is corrected in the next step.
  6) (OPTIONAL) Apply 70% Isopropyl alcohol to a small cloth and gently blot to smooth the wound surface. You should be able to get a smooth surface with a few blots.
  7) Mist area with baby oil. Wait a bit. Gently blot off excess with clean material.
  8) Dust liberally with baby powder.
  9) Wash off excess powder if necessary.
  10) Allow several hours for a complete cure.

This results in a smooth surface with a join that appears as strong and flexible as the original TPE. You might be able to add surface texture by blotting with fine sandpaper instead of a clean cloth. I have not tested that yet, but it looks interesting. Note the OPTIONAL steps should be tested first on your doll TPE. Some work as expected, other not so well. The key is a LIGHT wetting to smooth and bring edges together. Too much is not a good thing.

Now since all TPE seems to be slightly different, you should test and confirm on a hidden area before trying it on visible part of your doll. So far I have tested this successfully on dolls from WM, Kimber, JellyDoll, JellyNew, TPE sex toys and several other dolls of unknown type. All of those worked well. But you need to test on your own doll in an inconspicuous spot, since your mileage may vary.

The primer is available from multiple sources; Amazon currently lists an 8oz (236 ml) can for about $20. For TPE glue / cold weld use that is very reasonable. However, that is probably more than a lifetime supply (unless you are REALLY rebuilding a doll from scratch). If you get a full can, just place a small amount in a little container for doll use and re-seal the rest. Local auto repair, auto body or paint shops may sell or even give you a small amount for testing. The rest of the stuff is common household items that you may already have.

More later with some before/after from test repairs.
Hope it helps.
Cheers!
… W ….

[seagull]

Added this to my resource file

[seagull]

Safety Data Sheet for 3M 94 Primer
https://embossingtapesupplies.com.au/am ... ct_id/930/
Use with protective gear
Available in 8oz (236 ml) can or Pen Applicators

[Wheezer]

Thanks for posting the SDS. Lots of warnings and folks should know to be careful with this.

If you are applying this to a wide area or all day use in an enclosed space, the vapors would not really nice and protective gear would be wise. However in this case you place about 10-15 ml in a bottle and seal the rest up for later use. Actual application is via toothpick. You can actually can tell the level of curing by the odor. Listed flash time is 5 minutes, so give it a few hours and full cure. More cure time is always better.

The pen applicators do not seem to be an option. Each applicator contains a small glass tube with the primer inside. Break the tube and it flows to the pen tip. A one use option. And sticking that pen tip into a wound .... well no control over the fluid.

But just to be safe I guess one should always work in a well ventilated area and avoid sparks or open flames. Don't smoke or eat while using it. Wash your hands afterwards. Typical standard safety precautions.

Cheers!
... W ...

[Arthur1960]

Hi and thanks for posting this. Certainly sounds promising, after a quick look on ebay I found several sellers of this here in the UK and one in Belfast sells it in small dropper bottles right down to 5ml so I've just ordered 10ml size for the princely sum of £5.99, I figure at that price it's worth a try, timely as well as have a hand repair to do so will post my results in my repair thread.

[Mr Franz]

How about posting some pics of your test pieces so we can see the results?

[stacy718]

Great!

Now come fix my last two remaining TPE dolls for me, before I have to toss them!

[djcdoll]

Hi and thanks for posting this. Certainly sounds promising, after a quick look on ebay I found several sellers of this here in the UK and one in Belfast sells it in small dropper bottles right down to 5ml so I've just ordered 10ml size for the princely sum of £5.99, I figure at that price it's worth a try, timely as well as have a hand repair to do so will post my results in my repair thread.

I wonder if this stuff will be good at helping to seal up the cut holes in dolly hands following finger repairs?
I'll be watching to see how well this works out.

[Wheezer]

Thanks for the feedback and questions ....

Arthur1960 - Great to see you can get a small vial for testing. A 10 ml bottle will go a ways. A dropper bottle MIGHT work if the delivery is small enough. Otherwise use a toothpick (or whatever they call those little wooden meat spikes in the UK)

Mr Franz - I will be posting pics and a write up of a test repair on an actual doll, a Kimber. They say she uses "brand new mixture" a "proprietary blend" of TPE. This has been my worst case to glue with other stuff, so it made sense to do a live trial on her. The write up is almost finished. Should I post as new topic or continue in this one?

Here is a picture of what the target area for my next post on using it on a real doll. I figured a deep opening in a high stress area would be a good test.

00_Test_Damage.jpg (62.89 KiB) Viewed 14418 times

Thanks!
... W ...

[Wheezer]

How about posting some pics of your test pieces so we can see the results?

That's a reasonable request. Here is how it worked on my Kimber ....

3M 94 Primer – Test results with a TPE Kimber Doll

Testing the potential of a TPE Glue/Cold weld on test pieces, hidden areas and such is one thing, but it only counts if it can repair a damaged doll. So it makes sense to do a real test on a doll that has previously been a challenge to repair. Plus work on a high stress area that is highly visible. What could go wrong?

The Kimber is a good sculpt and they are correct when they state it is a proprietary TPE blend. They use a very soft material that has been a challenge to repair. Plus something that acts like an outer skin and reacts differently than the underlying TPE. The reaction may also have been caused by the prior failed repairs. My typical glue that works on WM and other dolls did not fare well with her, so it seemed appropriate to test the 3M primer.

She has an area with damages that started as small cuts, but rapidly enlarged. Being in the knee area any flex just made it worse. It was interesting to see the knee joint inside, but also somewhat ghastly. However it seems a good stress test. When closed there was one clean join, one semi-ragged join and two that did not close completely. Thus this was a good selection of different items to join. Plus all of these areas would be under a lot of tension when the knee bends.

This is the damaged knee area when compressed. The yellow marks around the wounds are remnants of prior failed repairs. Failure is a good thing; it shows what does not work and where to go next.

01_(CLOSED)20200809_150301(sm).jpg (479.62 KiB) Viewed 14398 times

The repair tools were basic and simple, those items pictures below and some baby powder.

02_(TOOLS)20200808_230118(sm).jpg (948.69 KiB) Viewed 14398 times

For testing I used all the steps listed in the prior post, even the optional ones. For a Kimber, probably skip those steps or greatly minimize them. They did not work as well as with other TPE blends.

The following are before and after images of the damage are and repair results. In each case the knees was flexed to place stress on the repair area.

BEFORE_AFTER(01).jpg (374.14 KiB) Viewed 14398 times

BEFORE_AFTER(02).jpg (192.86 KiB) Viewed 14398 times

BEFORE_AFTER(03).jpg (398.8 KiB) Viewed 14398 times

Results:
The 3M primer appears to work well as a TPE glue/Cold weld. The joins are solid, flexible and resist tension quite well. Placing the solution on the surface to join the edges did a cause a little deformation to the TPE. However there are many methods to smooth them out. My primary focus was to see strength and flexibility of the joins. They work well.

The last pic may look odd, this was the worst join area of all of them and I may have uses excess powder. I sort of went “Tammy Faye Baker” on that part. Unlike other areas the powder did not set in well with the oil mist and looks a bit odd. Another project in the prototype phase is an oil dye. Once I get that completed I can just color an area or wound with the oil solution that would go into the TPE, rather than makeup sitting on top. The goal is the ease of oil set powders all in one step. I plan on that for wound damage toning, tan lines and general coloration, highlighting and makeup.

So the 3M primer tests indicate that this has significant potential and works on a real doll in a high stress area. Those impacted by the shipping disruptions now have an option to try for repair and welding of TPE. I’m glad this seems to have passed testing, since I have labia repair, hand replacements, nipple upgrades and other thing waiting that can now get started.

The final result may not be perfect (as can be seen in the other results from many highly experienced repair folks on this board), but here I fall back on a term I used a lot: “Don’t let perfection be the enemy of the good”.

Hope this helps and post your test results if you try it yourself.
Cheers!
… W …

[Mr Franz]

Thanks, that was very helpful and looks quite promising so far!

[justintime]

I had to look away at first. That hurt my knee just to see that.
But it sure looks like you did a really good job on those repairs.
Will be interesting to hear how they are holding up after a bit of time.

[Wheezer]

Thanks for the feedback.

I was hesitant at first to post any of this. My preferred method would have been to do all the repairs, age them for 6 to 12 months and subject them to flex, compression, heat, moisture and other environmental effect. THEN mention it.

But since getting dolls and some repair stuff may get more challenging, it seemed OK to release the info early. With the caveat that it is free info, test it yourself, be careful and the rest. If Arthur1960 and others get some and try it and test it too that would be a good thing. It seems not only are the different dolls and blends subtly different, but based on the age what an owner may have done also comes into play. A lot of oil, powder, how they have cared for them etc.

If it helps some other folks, then I am happy. I got a lot of good information, feedback and such that have helped me from the members. Gotta give back.

Cheers!
... W ...

[hyrim]

That was a great read, thank you for passing on the knowledge and providing great info/pics. I loved your results!

[Anung Un Rama]

You may be able to smooth and blend further with mineral oil and a hot gun feathering over the repair area to about 110 to 120 degrees C tpe surface temp.

Also the current kimber blend is SEEPS Septon 4055 http://www.matweb.com/search/datasheett ... ae34cc6273

and here is the SDS https://www.b2bcomposites.com/msds/ted/60800.pdf

Anung